The present invention relates to a method of manufacturing a color-converting filter that enables multi-color display. The color-converting filter can be used for display in image sensors, personal computers, word processors, televisions, facsimiles, audio equipment, video equipment, car navigation equipment, desk-top electronic calculators, telephones, mobile terminal equipment, industrial measuring equipment, and so on.
In recent years, as one method of achieving multi-color or full-color display, a color conversion method in which color-converting colorants that absorb near ultraviolet light, blue light, blue/green light or white light, carry out wavelength distribution conversion, and emit light in the visible region are used as filters has been studied (see Japanese Patent Application Laid-open Nos. 8-279394 and 8-286033). In the case of using the color conversion method, the color of the light emitted by the light source is not limited to being white, and hence the degree of freedom of selection of the light source can be increased. For example, an organic EL light emitter that emits blue light can be used, and green and red light can be obtained through the wavelength distribution conversion. The possibility of constructing a full-color luminescent-type display for which a light source having improved efficiency can be used, and moreover even low-energy radiation such as near ultraviolet light or visible light can be used, has been studied (see Japanese Patent Application Laid-open No. 9-80434).
An important problem in terms of practical application to a color display is providing a color-converting filter that enables detailed color display and is stable in terms of color fidelity and so on over a prolonged period, and moreover has high color conversion efficiency. However, if the concentration of the color-converting colorants is increased to increase the color conversion efficiency, then a drop in the efficiency due to so-called concentration quenching, and decomposition of the color-converting colorants over time and so on will occur. Therefore, currently the desired color conversion efficiency is obtained by increasing the thickness of the color-converting layers containing the color-converting colorants. Introduction of a bulky substituent onto the colorant nucleus has been studies as a way of preventing concentration quenching and decomposition of color-converting colorants (see Japanese Patent Application Laid-open Nos. 11-279426, 2000-44824, and 2001-164245). Moreover, addition of a quencher has been studies as a means of preventing decomposition of color-converting colorants (see Japanese Patent Application Laid-open No. 2002-231450).
In order to increase the level of detail of a multi-color or full-color display that uses the color conversion method, it is necessary to carry out highly detailed patterning of the color-converting layers. However, in cases where the width of each line in the pattern is less than the film thickness of the color-converting layers, the reproducibility of the pattern shape, and deformation of the pattern during subsequent manufacturing steps become problems. In addition, in the case where patterning is carried out using ordinary photolithography, an application step, an exposure step carried out while aligning the mask, and a developing step are required for each color of color-converting layers. Thus, in order to obtain a full-color display, at least red, green and blue color-converting layers are required, and hence the manufacturing process requires many steps, and is complex.